<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div span {
            color: red;
        }
    </style>
</head>

<body>
    <div>
    </div>
    <script>
        console.log(location.search);
        var usname = location.search
        console.log(usname);
        var usw = usname.substr(1)
        console.log(usw);
        var arr = usw.split('=')
        console.log(arr);
        var div = document.querySelector('div')
        div.innerHTML = '<span>' + arr[1] + '</span>' + '欢迎回来'
    </script>
</body>

</html>